Frozen beverage machine control system and method

ABSTRACT

A method of operating a frozen beverage machine is disclosed that utilizes a short “burst” heating of the beverage machine&#39;s freezing chamber. The method includes monitoring a beverage mixture within the freezing chamber of the frozen beverage machine, and heating the freezing chamber for a predetermined time period in response to the beverage mixture reaching a first predetermined state. The freezing chamber is then refrigerated until the beverage mixture reaches a second predetermined state.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/908,505, filed on Jul. 18, 2001, which claims the benefit ofU.S. Provisional Patent Application No. 60/219,591, filed on Jul. 20,2000. These applications are both incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to frozen beveragemachines and more particularly to an improved method of controlling theconsistency of the beverage produced by a frozen beverage machine.

[0004] 2. Description of Related Art

[0005] Frozen beverage machines are known in the art and have been usedfor years. These devices produce, for example, a frozen carbonatedbeverage by freezing a mixture of ingredients typically including syrup,water and carbon dioxide in a freezing chamber. The mixture freezes onthe inner surface of the chamber, which is surrounded by a helical coilthrough which a refrigerant passes. A rotating shaft is disposed insidethe chamber which has a plurality of outwardly projecting blades thatscrape the mixture off the inside wall of the freezing chamber. Once thecarbonated beverage is in the desired frozen state, the product isdispensed from the chamber through a product valve.

[0006] A control system controls the refrigeration system to maintainthe temperature of the ingredients within the freezing chamber. Smallice crystals that are formed during the initial freezing process willcontinue to grow to larger crystals. These larger ice crystals presentsignificant quality and operational problems with the frozen beveragemachine.

[0007] First, since the consistency of a frozen beverage is determinedto a large extent by the amount and size of the ice crystals present inthe beverage mix, the texture and consistency of the dispensed frozenbeverage will over time deteriorate and will thus likely becomeobjectionable to a consumer. Further, the ice crystals can attach andfreeze on surfaces inside the freezing chamber causing maintenance andother operational problems, and the ice crystals can stop or reduce theflow of the beverage out of the machine's dispensing valve. Stillfurther, the instrumentation systems that control the operation of themachine do not function as well due to the larger ice crystals presentin the frozen beverage mixture. The beverage then does not flow well sothat it can be controlled and produce a consistent drink.

[0008] In an attempt to alleviate these and other problems associatedwith the formation of large ice crystals in the freezing chamber, knownfrozen beverage machine systems completely defrost the beverage mixturein the freezing chamber. The frozen beverage mixture is returned to aliquid state on a periodic basis (typically every three to six hours),and then the mixture is refrozen. This removes the larger ice crystals.The defrost and refreeze process typically takes from five to 30 minutesor longer. Unfortunately, when the mixing chamber is defrosting, noproduct can be served to the consumer. This results in lost sales andunhappy customers.

[0009] The present invention is directed to improved frozen beveragemachine operation methods which overcome, or at least minimizes,problems associated with the prior art.

SUMMARY OF THE INVENTION

[0010] The present invention provides methods for operating a frozenbeverage machine so as to improve the consistency of drinks produced bysuch machines. It is beneficial to extend the time between defrostcycles, or even to eliminate the complete defrost cycles associated withprior art systems entirely, to keep the frozen beverage machine operablewithout interruption. The operation of the machine and the quality ofthe product must not substantially deteriorate during the extendedperiods of no complete defrost. To improve drink consistency, a novelmodification to frozen beverage machine operation is disclosed. Insteadof employing a defrost cycle that takes the frozen product completelyback to a liquid state, the freezing chamber of the frozen beveragemachine is heated for a shorter time period on a more frequent basis.This “burst” heating of the freezing chamber can control the size of icecrystals and create advantages to improve the operation of the frozenbeverage machine, and in turn, improve the consistency of the beverageproduced.

[0011] In one aspect of the present invention, the burst heating isconducted on a frequent basis to maintain a consistent frozen drink toreduce the size and amount of ice crystals in the freezing chamber of afrozen beverage machine. The frozen beverage mixture within the freezingchamber approaches a less frozen state, but is not taken to a liquidstate as in known defrost cycles, thus maintaining the beverage mixturein a desired consistency.

[0012] In an exemplary method of operating a frozen beverage machine inaccordance with the invention, the freezing chamber is monitored, andthe freezing chamber is heated for a predetermined time period (lessthan 15 seconds in some embodiments) each time the compressor is to beturned on to refrigerate the freezing chamber. The freezing chamber isthen refrigerated until the beverage mixture reaches the desiredconsistency.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other objects and advantages of the invention will becomeapparent upon reading the following detailed description and uponreference to the drawings in which:

[0014]FIG. 1 is a block diagram of portions of a frozen beveragemachine;

[0015]FIG. 2 is a flow diagram illustrating a prior art refrigerationcycle of a frozen beverage machine;

[0016]FIG. 3 is a flow diagram illustrating a method of operating afrozen beverage machine in accordance with aspects of the presentinvention; and

[0017]FIG. 4 is a block diagram illustrating a frozen beverage machinein accordance with embodiments of the present invention.

[0018] While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Illustrative embodiments of the invention are described below. Inthe interest of clarity, not all features of an actual implementationare described in this specification. It will of course be appreciatedthat in the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

[0020]FIG. 1 is a simplified block diagram schematically illustratingcomponents of a typical frozen beverage machine 10. The frozen beveragemachine 10 includes an ingredients supply source 12, a controller 14, aprocess flow block 16, at least one freezing chamber 18 and arefrigeration system 20. The ingredient supply source 12 may include,for example, a water supply tank, syrup supply tanks and a carbondioxide tank.

[0021] Ingredients for a frozen beverage mixture are provided from theingredient supply 12 to the process flow block 16, which controls theflow of the ingredients into the freezing chamber 18 as directed by thecontroller 14. The controller 14 may comprise an appropriatelyprogrammed microprocessor and suitable memory devices encoding programinstructions for executing the processes described and illustratedherein. The operation of the control block 16 and other controlinstrumentation is described, for example, in U.S. Pat. No. 5,706,661issued to the present inventor, and which is incorporated by referenceherein in its entirety.

[0022] The refrigeration system 20 functions to keep the beveragemixture within the freezing chamber 18 at the desired consistency, andmay also be controlled by the controller 14. The beverage mixture withinthe freezing chamber 18 is refrigerated such that it freezes on theinner surface of the freezing chamber 18. A rotating shaft (not shown inFIG. 1) is disposed inside the chamber and blades extending outwardlytherefrom scrape the mixture off the inside wall of the freezing chamber18. Once the beverage is in the desired frozen state, the product isdispensed from the chamber 18 through a dispensing valve.

[0023]FIG. 2 is a flow diagram illustrating a typical refrigerationcycle for the freezing chamber 18 of the frozen beverage machine 10. Inblock 110, the beverage mix within the freezing chamber 18 ismonitored—any of a number of variables associated with the beveragemixture and/or freezing chamber 18 may be monitored to determine thecondition of the beverage mixture. Typically, the beverage mixture ismonitored to determine whether it is in a frozen or liquid state. If themixture has reached a predetermined “thaw” point in decision block 112,the refrigeration system 20 cools the chamber 18 (block 114) until thebeverage mixture reaches a “freeze” point as determined in decisionblock 116, at which point the refrigeration is stopped (block 118), andthe process repeats.

[0024] At periodic intervals, typically every three to six hours, thefreezing chamber is defrosted. The freezing chamber 18 is warmed so thatthe beverage mixture returns to an unfrozen, liquid state. Then thechamber 18 is refrigerated until the beverage mixture reaches a desiredconsistency. The defrost and refreeze process typically takes from aboutfive to 30 minutes. A separate heater may be provided to facilitate thedefrosting of the freezing chamber, or hot gas from the refrigerationsystem may be used to accomplish defrosting.

[0025] In accordance with the present invention, a short, or “burst”heating of the chamber 18 occurs on a regular, more frequent basis. Inone embodiment, the burst heating takes place each time therefrigeration system 20 cycles on to refreeze the chamber 18. As thefreezing chamber 18 sits for a period of time without the refrigerationsystem 20 freezing the liquid, the beverage mixture within the chamber18 approaches the less frozen thaw point. As discussed above, in knownfrozen beverage machines, the refrigeration system would then cycle onto refreeze the beverage mixture at this point (block 114 of FIG. 2).

[0026] With the system of the present invention, however, a burstheating is initiated when the beverage mixture reaches the thaw point.Thus, the burst heating is initiated in response to a monitored variableassociated with the beverage mixture and/or the freezing chamber 18,rather than completely defrosting the system at periodic time intervals.Moreover, the burst heating does not take the beverage mixture to acompletely liquid state as with known defrost processes, but rather,enables the larger ice crystals to melt out without reducing the qualityof the drink to an unacceptable frozen drink quality. The burst heatingmay be used in conjunction with full defrost cycles, or may be used inplace of the full defrost to eliminate the undesirable aspectsassociated with the full defrost.

[0027]FIG. 3 is a flow diagram illustrating aspects of a burst heatingcycle in accordance with embodiments of the present invention. As in theprior art refrigeration system illustrated in FIG. 2, the beverage mixis monitored by an appropriate means in block 120. The value of themonitored variable is compared to a first predetermined valuerepresenting the thaw point in decision block 122. Rather thanrefrigerating the chamber 18 upon reaching the thaw point, a burstheating is initiated in block 124 in response to the variable reachingthe predetermined thaw point in block 122. In an exemplary embodiment ofthe invention, the duration of the burst heating is less than 15seconds, though it may be longer. With the burst heating of the presentinvention, the beverage mixture does not reach a completely thawed,liquid state as in known full defrost processes. The burst heatingoperates to remove the larger ice crystals that form as the frozenbeverage mixture is contained in the freezing chamber 18.

[0028] Upon completion of the burst heating, the chamber 18 isrefrigerated (block 126) until the monitored variable reaches a secondpredetermined value (the freeze point), as determined in decision block128, at which time the refrigeration is ceased (block 130) and theprocess repeats.

[0029] The burst heating may be accomplished in several manners. Forexample, upon the beverage mixture reaching the thaw point, theinitiation of the refrigeration system may simply be delayed, thusallowing the temperature of the mixture to warm beyond the thaw point tomelt some of the formed ice crystals. Alternatively, the freezingchamber 18 may be heated using a heat source for a short period. Thismay be accomplished via a heater associated with the freezing chamber18, or by cycling hot gas from the refrigeration system 20 around thechamber 18.

[0030]FIG. 4 is a block diagram schematically illustrating portions of afrozen beverage system 11 in accordance with an exemplary embodiment ofthe present invention that uses the refrigerant to heat the freezingchamber 18. The system 11 includes a freezing chamber 18, and a rotatingshaft 22 having a plurality of outwardly projecting blades (not shown)is disposed inside the chamber 18. The shaft 22 is driven by a motor 24,such that the blades mix the ingredients and scrape the mixture off theinside wall of the freezing chamber 18.

[0031] The refrigeration system 20 includes a compressor 50, a condenser52, an expansion valve 54 and an evaporator coil 56 surrounding thefreezing chamber 18. The compressor 50 provides the motive force for theparticular refrigerant contained within the refrigeration system 20. Thecompressor 50 forces the refrigerant through the condenser 52, where therefrigerant vapor liquefies. The liquid refrigerant passes through theexpansion valve 54, expanding the high-pressure liquid refrigerant to alow-pressure vapor. The low-pressure, low-temperature refrigerantdischarged from the thermostatic expansion valve 54 is then directedthrough the evaporator coil 56 for absorbing heat and thus refrigeratingthe freezing chamber 18 surrounded by the evaporator coil 56.

[0032] The torque of the motor 24 is monitored to determine the state ofthe beverage mixture within the freezing chamber 18. When the mixture isin a more thawed, liquid state, the torque required to turn the shaft 22is relatively low. As the mixture becomes more frozen, more torque isrequired to turn the shaft 22. Thus, in such an embodiment, the variablemonitored in the flow diagram of FIG. 3 is motor torque (block 120).When the torque falls to a first predetermined level representing thethaw point in decision block 122, the burst heating is initiated.

[0033] The refrigeration system 20 of the exemplary embodimentillustrated in FIG. 4 further includes a hot gas bypass valve 58. Whenthe burst heating is initiated in block 124 of FIG. 3, the compressor 50is started and the hot gas bypass valve 58 is opened for a short period(less than 15 seconds in one embodiment), allowing the refrigerant tobypass the condenser 52 and expansion valve 54. Thus, the refrigerant isnot liquefied, but remains a hot gas. The hot gas is directed throughthe coil 56, warming the chamber 18. When the burst heating period iscompleted, the compressor 50 continues to operate, the hot gas valve 58closes, and the expansion valve 54 opens to refrigerate the freezingchamber 18 (block 126 of FIG. 3). The motor torque is monitored, andwhen it reaches a second predetermined level representing the freezepoint, the refrigeration is stopped as shown in block 130 and theprocess repeats.

[0034] In further embodiments, other variables are monitored todetermine the state of the beverage mixture, and the burst heating ofthe chamber 18 is then conducted in response to the measured variable.For instance, the temperature of the mixture may be monitored using anyappropriate means, such as a thermometer. The burst heating would thenbe initiated in response to the mixture temperature reaching apredetermined thaw temperature. Alternatively, the viscosity of themixture may be determined by monitoring an appropriate variable, withthe burst heating being initiated in response thereto.

[0035] The methods of operating frozen beverage machines disclosedherein thus provide a beverage having a stable consistency, resulting inan enhanced beverage product. Further, since the frozen beverage mixturewithin the freezing chamber is more consistent, the performance of theinstrumentation systems controlling the equipment operation is enhanced,resulting in the following benefits:

[0036] a) Liquid refill is controlled more consistently, which controlsthe pressure in the freezing chamber.

[0037] b) The thaw-freeze cycles are more consistent and produce animproved frozen drink.

[0038] c) When gases such as carbon dioxide are injected into thefreezing chamber to create a frozen carbonated beverage, the control ofthe instrumentation and the quality of the resulting drink is improved.

[0039] d) When the frozen beverage machine sits for an extended periodof time without a drink being dispensed, the “casual” drink is of higherquality due to the improved consistency of product throughout the frozenchamber.

[0040] e) The control of build-up of large ice crystals reducesfreeze-ups in the dispensing valve and in the inlet liquid orifice tothe freezing chamber.

[0041] f) The burst heating cycles keep the average temperature of themetal components of the freezing chamber from becoming too cold, thuspreventing or at least reducing ice accumulations effecting machineoperations.

[0042] Thus, the methods and devices of the disclosed invention,including implementation of short burst heating in frequent cyclesgreatly enhances the operation of the frozen dispenser and the qualityof the dispensed drink. Maintenance of the equipment is reduced due toimproved operation of the control instrumentation systems and mechanicalcomponents such as valves. Reduced downtime of the equipment will resultfrom reduction or elimination of extended defrost cycles required totake the frozen mixture to a liquid.

[0043] The particular embodiments disclosed above are illustrative only,as the invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Accordingly, the protection sought herein is as set forth inthe claims below.

What is claimed is:
 1. A method of operating a frozen beverage machine,comprising: monitoring a beverage mixture within a freezing chamber ofthe frozen beverage machine; flowing uncondensed refrigerant through acoil surrounding the freezing chamber in response to the beveragemixture reaching a predetermined state; and flowing the refrigerantthrough a condenser and an expansion valve and through the coil.
 2. Themethod of claim 1, wherein flowing the uncondensed refrigerant includesflowing the uncondensed refrigerant through the coil for a predeterminedtime period.
 3. The method of claim 1, wherein flowing the uncondensedrefrigerant includes opening a bypass valve so that the refrigerantbypasses the condenser and the expansion valve.
 4. The method of claim1, wherein the refrigerant is flowed through the condenser and theexpansion valve and through the coil until the beverage mixture reachesa second predetermined state.
 5. The method of claim 1, whereinmonitoring the beverage mixture includes monitoring the torque requiredto turn a shaft situated in the freezing chamber.
 6. The method of claim1, wherein monitoring the beverage mixture includes monitoring thetemperature of the beverage mixture.
 7. The method of claim 2, whereinthe predetermined time period is less than 15 seconds.
 8. A controlsystem for a frozen beverage machine having a freezing chamber, thecontrol system comprising: a processor connected to receive a signalindicating the state of a beverage mixture in the freezing chamber; amemory device connected to the processor, the memory device storingprogram to code that when executed by the processor implements a methodincluding: flowing uncondensed refrigerant through a coil surroundingthe freezing chamber in response to the beverage mixture reaching apredetermined state; and flowing the refrigerant through a condenser andan expansion valve and through the coil.
 9. A frozen beverage machine,comprising: a freezing chamber; an evaporator coil surrounding thefreezing chamber; an expansion valve connected to the evaporator coil; acondenser connected to the expansion valve; a compressor connected tothe condenser to force a refrigerant through the condenser, expansionvalve and evaporator coil; a bypass valve connected between thecompressor and the evaporator coil, the bypass valve having a closedposition in which the refrigerant flows through the condenser, expansionvalve and evaporator coil, and an open position in which the refrigerantbypasses the condenser and expansion valve; and a controller monitoringa beverage mixture contained in the freezing chamber, the controllerconnected to the bypass valve to set the bypass valve in the open andclosed position for a predetermined time period in response to thebeverage mixture reaching a predetermined state.